Python3000出たよ

とりあえず確認。

Python2.6の場合

>>> class Hoge:
...     pass
...
>>> Hoge.__base__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: class Hoge has no attribute '__base__'
>>>

Python3.0の場合

>>> class Hoge:
...     pass
...
>>> Hoge.__base__
<class 'object'>
>>>